Without limiting the scope of the invention, its background is described in connection with laparoscopic procedures, such as cholecystectomy, in connection with a hyperspectral imaging system used for medical tissues and in connection with new devices, tools and processes for the in vivo detection and evaluation of diseases and disorders.
The gallbladder is a small pear-shaped organ that stores and concentrates bile. The gallbladder is connected to the liver by the hepatic duct. It is approximately 3 to 4 inches (7.6 to 10.2 cm) long and about 1 inch (2.5 cm) wide. The function of the gallbladder is to store bile and concentrate. The bile emulsifies fats and neutralizes acids in partly digested food. A muscular valve in the common bile duct opens, and the bile flows from the gallbladder into the cystic duct, along the common bile duct, and into the duodenum (part of the small intestine).
The following are disorders of the gall bladder. Cholelithiasis is a disorder of the extrahepatic biliary tract related to gallstones resulting in the presence of stones in the gall bladder. Gall stones are bodies formed within the body by accretion or concretion of normal or abnormal bile components. Gall stones of various shapes and sizes are formed within the gall bladder. Cholecsytitis is the inflammation of the gall bladder. Cholecystitis is often caused by Cholelithiasis, with choleliths most commonly blocking the cystic duct directly which causes the gallbladder's wall to become inflamed. Extreme cases may result in necrosis and rupture, and could cause further infection and pain resulting from such inflammation. Inflammation often spreads to its outer covering, irritating surrounding structures such as the diaphragm and bowel. Cholecystitis usually presents as a pain in the right upper quadrant. Gall bladder Cancer is a relatively uncommon cancer that occurs in the gall bladder. If detected early, this cancer can be cured by removing the gall bladder.
Gall bladder diseases are marked with some or all of the following symptoms: severe and constant pain in the upper right abdomen which can last for days; increasing pain when drawing a breath; and, radiating pain to the back or occurring under the shoulder blades. About a third of patients have fevers and chills. Nausea and vomiting may also occur. Complaints of gas, nausea, and abdominal discomfort after meals are the most common, but they may be vague and indistinguishable from similar complaints in people without gallbladder disease. Moreover, gall bladder diseases may result in jaundice (yellowish skin), dark urine, lighter stools, or combinations thereof.
As the majority of patients incur gallstones along with a gall bladder disease, the diagnosis can usually be confirmed thorough ultrasound imaging, a safe, painless and non-invasive technique that uses high frequency sound waves to create an image of gallbladder and gallstones. Other diagnosis methods like X-Ray and other scanning technology may be used.
Cholecystectomy is one of the most common operations performed in United States. It is frequently used for the treatment of symptomatic gallstones. Cholecystectomy is the surgical removal of gall bladder. The two procedures utilized to surgically remove the gall bladder are Open Cholecystectomy and Laparoscopic Cholecsytectomy. The laparoscopic method is utilized more frequently. The choice of the procedure is made on individual basis. A Cholecystectomy is performed to treat Cholelithiasis and Cholecystitis.
In conventional Cholecsytectomy, a surgeon makes an incision approximately 6 inches long. The incision is made either longitudinally in the upper portion of the abdomen or obliquely beneath the ribs on the right side. During the procedure, drains may be inserted into the abdomen, which are usually removed while the patient is still in the hospital. Following a normal cholecystectomy, the patient may be in the hospital from one to three days post surgery. Normal activity can be resumed in about four weeks. In complicated cases normal activity can be resumed in about four to eight weeks. The procedure is very common and is successful most of the time. However, any surgery involves risk factor associated with it, which can cause complications. The most common associated risk with Cholecsytectomy is the injury to the common bile duct (CBD) which is hidden, as it lies below a layer of fat. Thus, it is the surgeon's expertise and judgment for locating the CBD and avoiding any injuries.
A laparoscope is a long and rigid tube that is attached to a camera and a light source. Before the laparoscope is inserted, the patient's abdomen is distended with an injection of carbon dioxide gas, which allows the surgeon to see the internal organs of the patient. With the help of the laparoscope and a video display, which guides the surgeon for the procedure, the surgeon is able to locate and perform a cholecystectomy. Other small incisions are made in the abdomen; two of them on the right side below the rib cage and one in the upper portion below the sternum or the breast. Many other sophisticated instruments are used to perform the procedure. For example, two instruments are used to grasp and retract the gall bladder and a third is used to free the gall bladder from its attachment. Once the gall bladder is free, the surgeon then removes it from the patient.
Under normal conditions, patients recover within a day or two; however, complications may still occur. The most common complication that can occur is the injury to common bile duct (CBD). This complication occurs in about 0.5% of cholecystectomies. Even though this complication is rare, it demands a better imaging technique that provides the surgeon with the precise location of the CBD during a cholecystectomy. The imaging technique should also be able to distinguish between the CBD and other tissue, providing a good contrast image.
During a cholecystectomy, one of the important problems faced by the surgeon is visibility of structures below the fat layer. Thus, it is the surgeon's experience which determines the approximate location of the bile duct. An imaging aid currently available for intraoperative bile duct visualization is an Intraoperative Cholangiography (IOC). This technique has hardly undergone substantial changes since its introduction by Mirizzi in 1937. (See Mirizzi P L. 1937 Operative Cholangiography Surg Gynaecol Obstet. 1937; 65; 702-710). Routine IOC performed with every cholecystectomy is one of the strategies used to reduce bile duct injuries. The rapidly advancing technology of nuclear imaging, diagnostic ultrasound, MRI and CT have also been used for the purpose of visualizing the bile duct. For diagnosis of hepatobiliary disease imaging techniques such as ultrasound and Magnetic Resonance Cholangiography (MRC) are frequently used. Endoscopic Retrograde Cholangiography (ERC) is another standard for visualization of the bile duct. Ultrasound is tolerated by patients and is cost effective. MRC is superior in visualizing the biliary system, does not require any contrast agent to visualize the bile ducts and dilatation and gallstones in CBD are easily detected. For patients with choedocholithiasis, endoscopic retrograde cholangio-pancreatography (ERCP) can be utilized. Selective use of preoperative ERCP has proven to be a good diagnostic tool, as well as a way to allow clearance of CBD stones when present. (See Qasim Al-qasabi et al. “Operative Cholangiography in Laproscopic Cholecystectomy: Is it essential”). One of the faster and widely available techniques is Computed Tomography Cholangiography (CTC). A multi-detector CT reports a sensitivity of 65%-88% and a specificity of 84%-97% to detect gallstones. With the development of multi-detetcor CT, the resolution of CTC exceeds that of MR. (See A Persson, N Dahlstrom, Ö Smedby and T B Brismar: “Three-dimensional drip infusion CT cholangiography in patients with suspected obstructive biliary disease: a retrospective analysis of feasibility and adverse reaction to contrast material”).
Most histological evaluation of living tissues typically involves fixation, sectioning, and/or staining to obtain samples which exhibit high quality images under microscopy. While this process is current the industry standard, the procedure is time consuming. It requires removal of tissue from the patient, processing time, and has inherent sampling error. In addition, the major limitation of this process is the delay in providing the surgeon with clinically relevant information at the time of surgery. Thus, new methods have been developed to complement existing modalities by providing the surgeon real-time information that could be used intra-operatively to identify suspect lesions.
One such method is hyperspectral imaging. Hyperspectral imaging is a method of imaging spectroscopy that generates a gradient map based on local chemical composition. Hyperspectral imaging has been used in satellite investigation of suspected chemical weapons production areas, geological features, and the condition of agricultural fields, and has recently been applied to the investigation of physiologic and pathologic changes in living tissue in animal and human studies. Hyperspectral imaging has also been used in medical applications and has been shown to accurately predict viability and survival of tissue deprived of adequate perfusion, and to differentiate diseased (e.g., tumor) and ischemic tissue from normal tissue.
One such example can be seen in United States Patent Application Publication No. 2007/0016079 (Freeman et al.). The '079 application describes methods and systems of hyperspectral and multispectral imaging of medical tissues. In particular, the '079 application is directed to new devices, tools and processes for the detection and evaluation of diseases and disorders such as diabetes and peripheral vascular disease, that incorporate hyperspectral or multispectral imaging.
Another example can be found in United States Patent Application Publication No. 2007/0002276 (Hirohara et al.). The '276 application describes spectral characteristics that reduce variation depending on the frequency of received light intensity, and is gentle on a subject's eye. The invention of the '276 application eliminates displacement between positions of respective spectral images of the same area even if a change in alignment occurs between the eye and apparatus during image capture. In the '276 application, an apparatus for measuring spectral fundus image includes: an illumination optical system having an illumination light source that emits a light beam in a specified wavelength range; a light receiving optical system for forming a fundus image on the light receiving surface of a photographing section; a liquid crystal wavelength tunable filter capable of choosing a wavelength of a transmitted light beam in a specified wavelength range; a spectral characteristic correction filter having a wavelength characteristic for correcting the wavelength characteristic of the emitted light intensity of the illumination light source and the transmission wavelength characteristic of the wavelength tunable filter so that the received light intensity on the light receiving surface is kept within the specified range; and, a data measuring section for taking the spectral fundus image data from the light receiving surface while changing the wavelength of the light beam passing through the wavelength tunable filter.
Yet another example is described in U.S. Pat. No. 7,199,876 (Mitchell) entitled “Compact Hyperspectral Imager”. Here, the '876 patent details a hyperspectral imager including: a first optical sub-system; at least one slit element; a second optical sub-system; at least one reflective dispersive element located at a center plane; and, at least one detecting element located at substantially an image surface. During operation, the first optical sub-system images, onto the slit element(s), electromagnetic radiation originating at a source. The second optical sub-system substantially collimates, at a center plane, electromagnetic radiation emanating from the slit element(s). The second optical sub-system also images, onto the image surface, the electromagnetic radiation reflected from the reflective dispersive element(s). The detecting element(s) detect the dispersed electromagnetic radiation reflected from the reflective dispersive element(s).
Still yet another example is seen in U.S. Pat. No. 7,167,279 (Otten) entitled “High Efficiency Spectral Imager”. The '279 patent describes optical instruments having, inter alia, optics to process wavelengths of electromagnetic radiation to produce an interferogram. The instruments described in the '279 patent include at least one optical path and optical elements positioned along this path for splitting and recombining the wavelengths which interfere with each other to produce a plurality of different fringes of different wavelengths. In one group, the optics include matched gratings which are positioned along the optical path outside of the interferometer optics to produce first and second sets of spectrally dispersed beams. The interferometer optics also include a beam splitter and first and second mirrors. The gratings may be positioned in a variety of locations along the optical path. In another group, the optics include a beam splitter having a plurality of surfaces, wherein each of the surfaces is either 100% reflective, 100% transmissive or 50% reflective and 50% transmissive. In a third group, the optics include the beam splitter having a plurality of reflective and transmissive surfaces and matched gratings. The instruments can all include a detector for detecting the interferogram and means for processing the detected interferogram to produce spectral information.
U.S. Pat. No. 6,198,532 (Cabib) discloses a spectral bio-imaging method for enhancing pathologic, physiologic, metabolic and health related spectral signatures of an eye tissue. The method disclosed in the '532 patent includes the steps of: (a) providing an optical device for eye inspection being optically connected to a spectral imager; (b) illuminating the eye tissue with light via the iris, viewing the eye tissue through the optical device and spectral imager and obtaining a spectrum of light for each pixel of the eye tissue; and, (c) attributing each of the pixels a color according to its spectral signature, thereby providing an image enhancing the spectral signatures of the eye tissue.
Another example can be found in U.S. Pat. No. 6,992,775 (Soliz et al.). The '775 patent discloses an ophthalmic instrument for obtaining high resolution, wide field of area hyperspectral retinal images for various sized eyes which includes a fundus retinal imager (which includes optics for illuminating and imaging the retina of the eye); apparatus for generating a real time image of the area being imaged and the location of the hyperspectral region of interest; a high efficiency spatially modulated common path; a Fourier transform hyperspectral imager (a high resolution detector optically coupled to the hyperspectral and fundus imager optics); and, a computer (which is connected to the real time scene imager, the illumination source, and the high resolution camera) including an algorithm for recovery and calibration of the hyperspectral images.
Finally, in U.S. Pat. No. 7,118,217 (Kardon el al.) describes an optical imaging device of retinal function to detect changes in reflectance of near infrared light from the retina of human subjects in response to visual activation of the retina by a pattern stimulus. The device of the '217 patent measures changes in reflectance corresponding in time to the onset and offset of the visual stimulus in the portion of the retina being stimulated. Any changes in reflectance can be measured by interrogating the retina with a light source. The light source may be presented to the retina via the cornea and pupil or through other tissues in and around the eye. Different wavelengths of interrogating light may be used to interrogate various layers of the retina. Additionally, various patterns and methods of stimulation have been developed for use with the imaging device and methods.
The aforementioned hyperspectral imaging systems are slow for routine clinical practice. In addition, there are no methods for directly imaging the in vivo level of the biomolecules in live humans or animals during clinical visits or during surgical (open, endoscopic or laparoscopic) operations. Accordingly, there is a need for an improved microscopy system and method that incorporates superior speed for hyperspectral/multimodal imaging while offering high spatial resolution and optimized signal sensitivity for fast image acquisition. The present invention is directed to such a need.